Spinal cord and the Periphery Flashcards

1
Q

what information is carried in the descending cords of the spinal tract

A

motor

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2
Q

where do the descending spinal tracts originate

A

cerebral cortex and brainstem

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3
Q

what are the descending tracts concerned with

A

control of movement, muscle tone, spinal autonomic functions

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4
Q

what happens to the descending and ascending tracts in the medulla

A

decussate to the opposite side

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5
Q

how many neurons are in the descending pathway

A

2

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6
Q

what information if carried in the ascending cords of the spinal tract

A

sensory

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7
Q

how many neurones are in the ascending pathway

A

3

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8
Q

what information is carried by the posterior/dorsal column

A

fine touch, tactile localisation, vibration sense, proprioception

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9
Q

where does information in the dorsal column cross over

A

upper medulla - pyramidal tracts

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10
Q

what is the main role of the thalamus

A

it is a sensory relay station (lateral nucleii)

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11
Q

what information is carried by the lateral spinothalamic tract

A

pain and temperature

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12
Q

where does information in the lateral spinothalamic tract cross over

A

at the level of entry

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13
Q

if a lesion occurs above the level of crossing over of tracts where is the deficit

A

the opposite side

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14
Q

if a lesion occurs below the level of the crossing over of tracts where is the deficit

A

on the same side

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15
Q

what is a reflex

A

an involuntary stereotyped pattern of response brought about by sensory stimuli

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16
Q

what are spinal reflexes

A

reflexes mediated at the level of the spinal cord

17
Q

anatomically what are the two types of reflex

A

monosynaptic - eg stretch reflex

polysynaptic - eg flexor relfex

18
Q

describe briefly what occurs in the stretch reflex

A
  1. tendon stretched
  2. intrafusal muscle fibres stimulated
  3. sensory neuron activated

4a. monosynaptic arc
4b. polysynaptci arc to inhibitory interneuron

5a. muscle contraction
5b. reciprocal innervation

19
Q

what is the stretch reflex important in the control of

A

muscle tone and posture

20
Q

what mediates both the stretch and flexor reflexes

A

lower motor neuron

21
Q

what happens to the stretch reflex in upper motor neuron lesions

A

exaggerated

reflex control by lower motor neuron so if upper motor neuron lesion - reflex not affected - becomes exaggerated

muscle tone also increases = spasticity

22
Q

what are presentations of upper motor neuron lesions

A

spastic paralysis with hyperreflexia

23
Q

what does the corticospinal/pyramidal tract control

A

voluntary skilled movements

24
Q

is motor neurone disease an upper or lower motor neurone condition

A

lower motor neurone (= ventral horn of the spinal cord)

25
Q

what happens in motor neuron disease

A

neuron dies - muscle supplied by it atrophies

progressive, incurable disease

26
Q

what does an UMN lesion ABOVE the decussation of the corticospinal/pyramidal tract cause

A

contralateral spastic paralysis

hyperreflexia

27
Q

what does an UMN lesion BELOW the decussation of the corticospinal/pyramidal tract cause

A

ipsilateral spastic paralyis

hyperreflexia

28
Q

what does a LMN lesion of the corticospinal/pyramidal tract cause

A

ipsilateral flaccid paralysis

arreflexia

29
Q

what does a lesion ABOVE the decussation of the posterior/dorsal column cause

A

contralateral sensory loss

30
Q

what does a lesion BELOW the decussation of the posterior/dorsal column cause

A

ipsilateral sensory loss

31
Q

what would the lateral spinothalamic tract of the RIGHT side carry

A

pan and temp from the LEFT side of the body

vice versa

32
Q

what would the posterior/dorsal column of the RIGHT side carry

A

touch, pressure, proprioception from the RIGHT side of the body

vice versa

33
Q

what would lesions in the lateral spinothalamic tract cause

A

both lesion would be ABOVE the decussation (cross at spinal level of entry) so pain and temp lost on the opposite side to lesion

34
Q

CASE EXAMPLE: Brown-Sequard syndrome

eg herniated disc (left side) of C3

= hemisection of the spinal cord on left side

what tracts would be abrupted and where

A

Pyramidal tract, spinothalamic tract, posterior column

all abrupted on left side

35
Q

CASE EXAMPLE: at the spinal cord level, are the abrupted tracts affected above or below their crossing

A

Pyramidal tract = below crossing

Spinothalamic tract =  above crossing

Posterior column = below crossing

36
Q

CASE EXAMPLE: what does the pyramidal tract hemisection cause

A

left ipsilateral spastic paralysis

UMN lesion
below crossing

37
Q

CASE EXAMPLE: what does the spinothalamic tract hemisection cause

A

right contralateral loss of pain and temp

lesions will always be above crossing

38
Q

CASE EXAMPLE: what does the posterior column hemisection cause

A

left sided ipsilateral loss of touch and vibration sense

below crossing

39
Q

CASE EXAMPLE: what will happen to the reflexes

A

pyramidal tract UMN lesion below decussation

= hyppereflexia on left ipsilateral side